Surgical Management for Posterior Atlantoaxial Dislocation without Fracture and Atlantoaxial Dynamic Test to Confirm the Integrity of the Transverse Ligament: A Case Report.

Background: Traumatic posterior atlantoaxial dislocation (PAAD) without fracture of the odontoid process is a rare injury. Closed reduction by skull traction under C-arm fluoroscopic guidance and open reduction have been reported previously for the treatment of PAAD.

Objective: To report a rare case of PAAD without fracture treated by closed manual reduction and posterior fixation. To provide a new method-atlantoaxial dynamic test-for confirming the integrity of the transverse ligament after reduction and evaluate the ideal treatment strategy for traumatic PAAD without fracture of the odontoid process or rupture of the transverse ligament.

Method: A 54-year-old woman was riding in the passenger seat when her vehicle was rear-ended by a car. X-ray and computed tomography (CT) scans were used to diagnose PAAD without a related fracture. Closed manual reduction under C-arm fluoroscopy was performed after applying general anesthesia via sober intubation, and the integrity of the transverse ligament was confirmed by the atlantoaxial dynamic test with C-arm fluoroscopy. Then, pedicle screw internal fixation via the posterior approach was applied to maintain atlantoaxial stability.

Results: The procedure was performed uneventfully, and the patient was able to move out of bed on the first day after surgery with Philadelphia cervical gear. During a 2-year follow-up period, imaging data demonstrated no instability of the atlantoaxial complex.

Conclusion: Closed manual reduction under C-arm fluoroscopy is an easy and effective method for PAAD. The integrity of the transverse ligament can be confirmed by C-arm fluoroscopy through the atlantoaxial dynamic test after reduction. Pedicle screw internal fixation via the posterior approach can provide sufficient stability.